Yellowjackets

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Yellowjacket or Yellow Jacket Wasps Yellowjacket wasps often become a nuisance as they build up in large nests and scavenge for human food. This is the wasp that you often see buzzing around outdoor garbage cans, open soft drinks, ripe fruits and vegetables, candy, ice cream, etc. Yellowjackets are considered quite beneficial to agriculture since they feed abundantly on harmful flies and caterpillars, however their hyper-aggressive tendancy to attack in large numbers makes them a real nuisance insect to most people. Eliminating a yellowjacket nest is a matter that should be completed by a qualified pest control company.

Yellowjacket Identification

A typical yellowjacket worker is about 1/2" long, short and blocky, with alternating black and yellow bands on the abdomen while the queen is larger, about 3/4" long. (The different black and yellow patterns on the abdomen help separate various species.) Workers are sometimes confused with honey bees, especially when flying in and out of their nests. Yellowjackets, in contrast to honey bees, are not covered with tan-brown dense hair on their bodies and lack the flattened hairy hind legs used to carry pollen. Yellowjackets have a lance-like stinger without barbs and can sting repeatedly whereas honey bees have a barbed stinger and sting only once. Some have yellow on the face. Mouthparts are well-developed for capturing and chewing insects with a tongue for sucking nectar, fruit and other juices. Nests are built in trees, shrubs or in protected places such as inside human-made structures (attics, hollow walls or flooring, in sheds, under porches and eaves of houses), or in soil cavities, mouse burrows, etc. Nests are made from wood fiber chewed into a paper-like pulp.

Yellowjackets are social wasps living in colonies containing workers, queens and males. Colonies are annual with only inseminated queens overwintering. Fertilized queens occur in protected places as hollow logs, in stumps, under bark, in leaf litter, in soil cavities and human-made structures. Queens emerge during the warm days of late April or early May, select a nest site and build a small paper nest in which eggs are laid. After eggs hatch from the 30 to 50 brood cells, the queen feeds the young larvae for about 18 to 20 days. Larvae pupate, emerging later as small, infertile females called workers. By mid-June, the first adult workers emerge and assume the tasks of nest expansion, foraging for food, care of the queen and larvae, and colony defense. From this time until her death in the autumn, the queen remains inside the nest laying eggs. The colony then expands rapidly reaching a maximum size of 4,000 to 5,000 workers and a nest of 10,000 to 15,000 cells in August and late September. At peak size, reproductive cells are built with new males and queens produced. Adult reproductives remain in the nest fed by the workers. New queens build up fat reserves to overwinter. Adult reproductives leave the parent colony to mate. After mating, males quickly die while fertilized queens seek protected places to overwinter. Parent colony workers dwindle, usually leaving the nest and die, as does the yellowjacket queen.

Abandoned nests rapidly decompose and disintegrate during the winter. Nests inside structures will persist as long as they are dry. Nests are not used again. In the spring, the cycle is repeated. (Weather in the spring is the most important factor in colony establishment.) Although adults feed primarily on items rich in sugars and carbohydrates (fruits, flower nectar and tree sap), the larvae feed on proteins (insects, meats, fish, etc.). Adult workers chew and condition the meat fed to the larvae. Larvae in return secrete a sugar material relished by the adults. (This exchange of material is known as trophallaxis.) In late autumn, foraging workers (nuisance scavengers) change their food preference from meats to ripe, decaying fruits since larvae in the nest fail to meet requirements as a source of sugar.

The German yellowjacket builds a grey, brittle, papery soccer or football shaped nest in structures with the peak worker population between 1,000 to 3,000 individuals between May to November. The Eastern yellowjacket builds a tan, fragile papery soccer or football shaped nest underground with the peak worker population between 1,000 to 3,000 individuals between May to November similar to the Common yellowjacket. Nests are built entirely of wood fiber (usually weathered or dead) and are completely enclosed (football or soccer shaped) except for a small opening (entrance) at the bottom. The nest may be located below the soil or aerial with the paper envelope covering containing multiple, horizontal tiers of combs (10 or more) within. Larvae hang down in combs.

It is always best to avoid unnecessary stings. Should a yellowjacket wasp fly near you or land on your body, never swing or strike at it or run rapidly away since quick movements often provoke attack and painful stings. When a wasp is near you, slowly raise your hands to protect your face remaining calm and stationary for a while and then move very slowly (avoid stepping on the ground nest), backing out through bushes or moving indoors to escape. Never strike, swing or crush a wasp or bee against your body since it could incite nearby yellowjackets into a frenzied attack. Wasp venom contains a chemical pheromone signals guard wasps to come and sting the "wearer".

Be careful not to cut weeds or run the lawnmower over a ground nest nor disturb a nest in a tree or eaves of the home. Any noise and disturbance will sometimes infuriate and provoke painful stinging. Keep children away from any nests, and teach them to never hit or disturb the nest. Individuals should avoid attracting insects by not wearing perfume, or scented hygiene or personal care items when visiting areas where yellowjackets are expected to be found. Clothing with brightly colored, flowery prints with bright yellow, light blue, orange, fluorescent red colors also attract yellow jackets.

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